Baclofen is sold under the brand names Lioresal and Gablofen. It is a muscle relaxant that is used to treat muscle spasticity associated with disorders like multiple sclerosis or spinal cord injuries. The majority of the drug is eliminated via the urine. Special tests may be able to detect the presence of baclofen for up to four days after use.
Most people who use baclofen take it in pill form in multiple doses throughout the day. Typically, individuals are administered the smallest dose possible that can produce the needed medicinal effects.
In addition to being used as a muscle relaxant, the drug has also been used off-label in other capacities, including to treat withdrawal from alcohol and other substances.
Mechanism of Action
The specific mechanism of action for baclofen is not well understood, but it is believed to affect the availability of the neurotransmitter gamma-aminobutyric acid (GABA), particularly the GABA-B receptor.
GABA is the major inhibitory neurotransmitter in the brain. When it is activated, it reduces the activity of the neurons in the brain and spinal cord. This reduction in the firing rates of the other neurons accounts for its ability to treat muscle spasticity and stiffness.
As a result, it may also lead to sedation and problems with motor coordination and thinking in some individuals.
There are some scattered reports of baclofen abuse, particularly in people who chronically abuse substances that may mix baclofen with other drugs like alcohol. However, baclofen is not a major drug of abuse.
Its chronic abuse may produce significant tolerance and may be associated with physical dependence. People using the drug for medical reasons typically use it for a short time. When it is time to discontinue the drug, the dosage is slowly tapered down by their physician.
Half-Life of Baclofen
The half-life of a drug refers to the amount of time it takes a person’s metabolism to reduce the concentration of the drug in the bloodstream to half its original amount.
The half-life of baclofen is relatively short, and for most people, it ranges between two and four hours.
Under normal conditions, most substances are fully metabolized and eliminated from the system over a period of five to six half-lives. Baclofen is primarily excreted in the urine without being metabolized (between 70 and 80 percent of the drug), and about 15 percent of the drug is metabolized in the liver.
This is why multiple doses of the drug are needed throughout the day for medical treatments.
Detectability of Baclofen
Baclofen is usually detectable in urine tests for up to two days, although individuals taking large amounts of the drug may have a longer window of detectability.
Blood tests may reveal the presence of baclofen for up to 24 hours, depending on specific individual factors.
Hair follicle tests typically have a longer window of detectability for most drugs. They may be able to detect the presence of baclofen for up to 90 days, although most of these tests do not typically screen for baclofen.
Other factors that can affect the detectability of baclofen include the individual’s body mass (weight), their age, how long they have regularly used the drug, whether or not baclofen is used in conjunction with other substances like alcohol (which can slow down the elimination of the drug), and individual differences in metabolism.
Do Drug Tests Typically Screen for the Presence of Baclofen?
A person taking a single dose of baclofen will normally eliminate the drug from their system 10 to 20 hours after taking the medication. However, baclofen is not a drug that is screened for in the majority of drug tests. There are special tests that can screen for the presence of baclofen or the amount of baclofen in a person’s bloodstream. These specialty tests are not standard.